As well known, the importance of ultra-precision positioning technology has gradually increased in a variety of industrial fields. In particular, the development of semiconductor technology results in high integration of circuits. Consequently, a line width for use in the latest microprocessor is in the order of 0.18 μm which is 1/500 times as large as the diameter of a hair. In such a case, the accuracy required for a wafer manufacturing stage should meet reproducibility requirements of 20 nm that is 1/10 times as large as the line width. Further, an ultra-precision feeding apparatus implemented in the submicron order can be utilized in ultra-precision measurement fields, such as an atomic force microscope (AFM) and a scanning electron microscope (SEM), and in industrial fields including the information industry, and thus, it has a wide range of application.
A general positioning apparatus using a linear motor, or a servomotor and a ball screw has a relatively long stroke. However, it has a limitation on implementable positional accuracy due to a structural limitation such as backlash. The general positioning apparatus also has a disadvantage in that the height of the entire system is increased since an actuator is arranged vertically to obtain a vertical motion. This leads to many difficulties in controlling a vertical position in works requiring high accuracy.
Meanwhile, the ultra-precision positioning apparatus for achieving a motion of submicron order should be designed in such a manner that there is no frictional portion to eliminate or minimize nonlinear factors. Further, in the ultra-precision positioning apparatus, the actuator itself should be constructed by a component that can be easily driven in the submicron order and has high repeatability. Moreover, it is necessary to design the ultra-precision positioning apparatus so that its height can be kept as low as possible.